Connection pad layouts

ABSTRACT

In an implementation of connection pad layouts, a connection assembly includes a substrate assembly and connection pads disposed thereon. The connection pads form a configuration such that each connection pad is configured to align with a different terminal of an interconnect that is warped or otherwise has a non-linear alignment of terminals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application and claims the benefit andpriority of U.S. patent application Ser. No. 10/698,604 filed Oct. 31,2003.

TECHNICAL FIELD

This invention relates to connection assemblies and, in particular, toconnection pad layouts.

BACKGROUND

FIG. 1 illustrates a top-view of a substrate assembly 100 and aconventional array 102 of connection pads 104 formed on the substrateassembly 100. The connection pads are typically laid out in an array 102such that rows of the connection pads 104 are parallel and collinear.The connection pads 104 are disposed on an upper surface 106 of thesubstrate assembly 100 to form an electrical connection with thin filmwiring formed on a surface of the substrate assembly 100, or withconductive vias formed within the substrate assembly 100.

The substrate assembly 100 can be formed as a ceramic substrate andimplemented to electrically connect semiconductor integrated circuitsand other electronic or microelectronic components. The integratedcircuits and electronic components can be interconnected by way ofconductive vias formed within layers of the ceramic substrate assembly100.

Interconnect terminals of an integrated circuit or electronic componentare soldered, or otherwise affixed with a conductive adhesive, to theconnection pads 104 to electrically couple the integrated circuit orelectronic component with conductive vias in the substrate assembly 100.Solder can be pre-formed on an interconnect terminal or on a connectionpad 104 and can be reflowed (e.g., heated to a liquid) to provide aconductive bond that electrically couples an interconnect terminal witha respective connection pad 104. This provides an electrical signalcommunication path between an electronic component and a conductive viain the substrate assembly 100 (coupled through a connection pad 104).

FIG. 2 further illustrates the substrate assembly 100 (a top view) andthe conventional array 102 of connection pads 104 shown in FIG. 1. Awarped interconnect 200 is shown positioned over the connection padarray 102 to illustrate that interconnect terminals 202 of the warpedinterconnect 200 do not all align with the conventional array 102 ofconnection pads 104. The warped interconnect 200 is shown “transparent”such that the interconnect terminals 202 and the connection pads 104 are“viewable” through the interconnect 200. Further, FIG. 2 does not showthe integrated circuit or electronic component that warped interconnect200 would interface to the substrate assembly 100.

Although the interconnect terminals 202 at a mid-portion of theinterconnect 200 do align with a respective connection pad 104, such asterminal 202(4) which aligns with connection pad 104(4), the terminals202 at the ends of the warped interconnect 200 do not accurately alignwith a respective connection pad 104. For example, interconnect terminal202(1) does not accurately align with connection pad 104(1), andinterconnect terminal 202(N) also does not accurately align with aconnection pad on the substrate assembly 100. These misalignedinterconnect terminals and connection pads reduce the effectiveness ofthe electrical connections, and with some of the interconnect terminals,there is no electrical connection. In addition to the misalignedinterconnect terminal 202(N) not having an established electricalconnection with a respective connection pad, the misaligned interconnectterminal may overlap and electrically connect with the wrong connectionpad, as shown in region 204.

Electronic devices continue to be manufactured smaller and/or moreportable, yet increasingly are more complex and multi-functional whichrequires more electrical interconnections between components in theelectronic devices. Substrate assemblies in these smaller electronicdevices have limited available surface area for componentinterconnection, while at the same time, more electricalinterconnections are needed to implement the many features that areavailable with these electronic devices. As a result, manufacturersutilize thin and elongated interconnects to electrically connect thecomponents in an electronic device when available substrate surfacespace is at a premium.

When these thin and less rigid interconnects are manufactured, theinterconnects tend to warp at one or both ends due to manufacturinginaccuracies, material variations, and/or non-uniform shrinkage of thematerial used to manufacture the interconnects. For example,differential shrinkage of multi-lead interconnects in a two-dimensionalarray occurs when a thin and long interconnect is fabricated with morecoring on one end or the other resulting in non-uniform shrinkage on theend with more plastic or interconnect material. When the warpedinterconnect 200 is positioned over the connection pad array 102, notall of the interconnect terminals 202 accurately align with therespective connection pads 104 thus reducing the connection density, ormanufacturing yields.

A conventional practice to ensure accurate alignment and electricalcontact with the interconnect terminals of an electronic component is tooversize all of the connection pads. However, oversizing the connectionpads to accommodate the worst case misalignment limits the number ofconnection pads that can be formed within the ever diminishing availablesubstrate surface space, thus reducing and limiting the connectiondensity.

BRIEF DESCRIPTION OF THE DRAWINGS

The same numbers are used throughout the drawings to reference likefeatures and components.

FIG. 1 illustrates a substrate and a conventional array of connectionpads.

FIG. 2 illustrates the substrate and conventional array of connectionpads shown in FIG. 1 where interconnect terminals of a warpedinterconnect do not accurately align with the conventional array ofconnection pads.

FIG. 3 illustrates an exemplary connection pad array for a warpedinterconnect according to one embodiment of connection pad layouts.

FIG. 4 further illustrates the exemplary connection pad array shown inFIG. 3 where the connection pads align with interconnect terminals of aninterconnect according to one embodiment of connection pad layouts.

FIG. 5 illustrates an exemplary connection pad array having connectionpads formed into a configuration to align with an interconnect accordingto one embodiment of connection pad layouts.

FIG. 6 further illustrates the exemplary connection pad array shown inFIG. 5 where the connection pads can align with interconnect terminalsof a straight interconnect or can align with interconnect terminals of awarped interconnect according to one embodiment of connection padlayouts.

FIG. 7 is a flow diagram that illustrates one embodiment of a method offabricating connection pads for connection to an interconnect that iswarped or otherwise has a non-linear alignment of terminals.

DETAILED DESCRIPTION

In an embodiment of connection pad layouts, connection pads can bedisposed on a substrate assembly in any number of configurations toaccommodate any shape of an interconnect, such as an interconnect thatis warped during manufacture for example. The connection pads can belaid out to align with interconnect terminals of warped interconnectswithout over-sizing or increasing the contact area of the connectionpads, which maintains a high connection density. The exemplaryconnection pad configurations described herein provide that aninterconnect having any layout of terminals (e.g., a warpedinterconnect) will be electrically coupled to conductive vias within asubstrate assembly by contact between the interconnect terminals and oneor more of the connection pads in a connection pad configuration.

FIG. 3 illustrates a top-view of a substrate assembly 300 and an array302 of connection pads 304 formed on the substrate assembly 300. Thesubstrate assembly 300 also has an array 306 of connection pads 308formed on the substrate assembly 300. The connection pads 304 and 308are disposed on a surface 310 of the substrate assembly 300 to form anelectrical connection with thin film wiring (not shown) formed on asurface of the substrate assembly 300, or with conductive vias (notshown) formed within the substrate assembly 300.

The substrate assembly 300 can be formed with layered sheets ofsubstrate material such as alumina, glass ceramic aluminum nitride,laminated glass fibers and epoxy for a PC board, layers of polymide fora flex circuit, or any other type of substrate material. The layeredsubstrate sheets can have conductive vias that are filled with aconductive material, plated or otherwise made conductive, toelectrically connect each conductive via to a respective connection pad304, 308. The connection pads 304 and 308, and the vias in substrateassembly 300, are multiple conductors which can be formed with suchconductive material as tungsten, molybdenum, copper, conductiveadhesive, brazing, or with any other type of conductive material.

Substrate assembly 300, which in one embodiment is a layered ceramicsubstrate, can be manufactured to electrically connect semiconductorintegrated circuits and other electronic or microelectronic components,such as printing device components. The integrated circuits andelectronic components can be connected by the conductive vias which mayfunction as electrical interconnections and can be formed within thelayers of the substrate assembly 300. The connection pads 304 and 308can be part of circuitry disposed on the substrate assembly 300, or canbe the connections for implementation within a larger circuit and/orelectronic component.

In an embodiment, connection pads 304 are disposed on substrate assembly300 in a configuration (e.g., connection pad array 302) with a warpvariance 312 which in this example, is a distance that one or both endsof an interconnect are displaced from a center of the interconnect. Inanother embodiment, warp variance 312 can also be determined, ormeasured, as a distance from a center of the connection pad array 302.In an additional embodiment, a warp variance 312 can be described as oneor more of the connection pads 304 having a center that is offset from aline in a direction parallel to a surface of the substrate assembly uponwhich the connections pads are disposed where the line is defined by aplane perpendicular to the surface of the substrate assembly. Othermethods of measuring or determining warp variance may be utilized.

In the example shown in FIG. 3, connection pad array 302 is laid outsuch that the connection pads 304 each align with the terminals of aninterconnect that is warped on both ends. Connection pad array 306 islaid out such that the connection pads 308 align with the terminals ofan interconnect that is straight on one end (aligns with connection pads308 in region 314) and that is warped on the other end (aligns withconnection pads 308 in region 316). In another embodiment, connectionpads 304 may be disposed in a configuration such that a line through acenter of the connection pads 304 in a row 318, and a line through acenter of the connection pads 308 in a row 320, is curvilinear or anarc.

The connection pad arrays 302 and 306 are only two examples ofconnection pad configurations that can be disposed on substrate assembly300 to accommodate any shape of warped interconnects having any warpvariance 312. The connection pads 304 and 308 are laid out to align withthe terminals of warped interconnects without over-sizing or increasingthe contact area of the connection pads to maintain a high connectiondensity when mounting warped interconnect(s) on a substrate assembly.

Although only the two connection pad arrays 302 and 306 are shown havingconnection pads 304 and 308, respectively, any number of connection padarrays which include any number of connection pads can be disposed onsubstrate assembly 300. Further, although the connection pads 304 and308 are shown as rectangular pads, the connection pads can beimplemented as any number of different shapes to align and coincide withany type of interconnect terminals. It should also be noted that thesubstrate assembly 300 and the connection pads 304 and 308 are onlyillustrative and are not shown to scale in the figures.

FIG. 4 illustrates the substrate assembly 300 and the connection pads304 and 308 as shown in FIG. 3. A warped interconnect 400 is positionedover the connection pads 304 (e.g., connection pad array 302) such thatinterconnect terminals 402 of the warped interconnect 400 align with theconnection pads 304. For example, interconnect terminal 402(1) alignswith a respective connection pad 304(1), interconnect terminal 402(2)aligns with a respective connection pad 304(2), and interconnectterminal 402(N) aligns with a respective connection pad 304(N).

A warp variance 404, in this example, is a distance that each of a firstend 406 and a second end 408 of the warped interconnect 400 is displacedfrom a center of the interconnect 400 due to warping, such as duringmanufacture. The warp variance 404 substantially aligns with warpvariance 312 (FIG. 3) which corresponds to the configuration layout ofconnection pad array 302 of the connection pads 304. The interconnect400 is warped in a direction 410 that is parallel to the surface 310 ofthe substrate assembly 300 (the surface 310 being the substrate surfacethat connection pads 304 and 308 are disposed upon).

A particular substrate assembly can include any layout of connectionpads to align with the interconnect terminals of any warpedinterconnect. For example, a substrate assembly can include connectionpad arrays 302 and 306 to align with the terminals of an interconnectwarped at both ends and an interconnect warped at only one end,respectively.

FIGS. 5 and 6 illustrate a top-view of a substrate assembly 500 and anarray 502 of connection pads 504 formed on the substrate assembly 500.The substrate assembly 500 also includes an array 506 of connection pads508 formed on the substrate assembly. Connection pads 504 are configured(e.g., disposed, or otherwise formed, on or in substrate assembly 500)to align with interconnect terminals 600 of a warped interconnect 602(shown in FIG. 6). Connection pad array 502 includes one or moreconnection pads 504 that are extended on one side (e.g., in region 510)and which are configured to align with the interconnect terminals 600 ofinterconnect 602. In this example, the interconnect 602 is warped suchthat the centers of the interconnect terminals 600 are not in a sameplane that is substantially normal to the surface of the interconnect602 (e.g., the centers of the interconnect terminals 600 are not alignedhorizontally along the array 502 of connection pads 504).

The connection pads 508 of connection pad array 506 are extended, orotherwise widened, on both sides to also align with the interconnectterminals of an interconnect (e.g., interconnect 702) which may bewarped at one end, at both ends, or warped in some other area. Althoughall of the connection pads 508 are illustrated as being extended on bothsides of the pads, any one or more of the connection pads 508 may beextended on one or both sides as applicable to accommodate a connectionwith an interconnect terminal of an interconnect. Further, any one ormore of the connection pads 508 may be extended a distance less orgreater than any other connection pad on one and/or both sides.

The connection pads 504 and 508 are disposed on a surface 512 of thesubstrate assembly 500 to form an electrical connection with thin filmwiring (not shown) formed on a surface of the substrate assembly 500, orwith conductive vias (not shown) formed within the substrate assembly500. Connection pad arrays 502 and 506 allow an interconnect having anyshape to be electrically coupled to conductive vias within the substrateassembly 500 by contact between the interconnect terminals and one ormore of the connection pads 504 and 508 (e.g., using solder).

FIG. 7 illustrates a method of fabricating connection pads forconnection to an interconnect that is warped, or otherwise has anon-linear alignment of interconnect terminals (e.g., the interconnectterminals are not horizontally centered in a plane that is substantiallynormal to the surface of the interconnect). The order in which themethod is described is not intended to be construed as a limitation, andany number of the described method blocks can be combined in any orderto implement the method.

At block 702, a substrate assembly is formed having conductive vias. Forexample, substrate assembly 300 (shown in FIG. 3) can be formed with atleast a surface 310, and can be formed as a multilayered ceramicsubstrate assembly with conductive vias.

At block 704, a warp variance of manufactured interconnects isdetermined. For example, warped interconnect 400 (shown in FIG. 4) has awarp variance 404 which is a resultant defect when the interconnect 400is manufactured and/or fabricated. The warp variance 404 can bedetermined as a manufacturing tolerance, or deviation, by whichconnection pad layouts can be designed to accommodate warpedinterconnects.

At block 706, connection pads are disposed on the substrate assembly ina configuration that aligns each connection pad with a differentterminal of a warped interconnect. For example, connection pads 304 and308 (shown in FIG. 3) are disposed on substrate assembly 300 in aconfiguration of connection pad arrays 302 and 306, respectively.Connection pads 304 each align with a different interconnect terminal402 (shown in FIG. 4) of the interconnect 400 such that the connectionpads 304 couple an interconnect terminal 402 with a conductive via inthe substrate assembly 300. The connection pads 304 and 308 can also beformed as solder pads each configured to form a soldered connection thatelectrically couples a terminal 402 of the interconnect 400 with aconductive via in the substrate assembly 300.

The connection pads 304 (shown in FIG. 3) are disposed on the substrateassembly 300 in the configuration according to the warp variance 404(shown in FIG. 4) of interconnect 400. For example, connection pad array302 is laid out with a warp variance 312 that substantially aligns withwarp variance 404 of the interconnect 400. An interconnect can be warpedat one end of the interconnect, or the interconnect can be warped atboth ends such as interconnect 400 which is warped on a first end 406and warped on a second end 408. The interconnect 400 is warped on bothends in a direction 410 that is parallel with surface 310 of thesubstrate assembly 300.

Further, connection pads 504 and 508 (shown in FIG. 5) are disposed onsubstrate assembly 500 in a configuration of connection pad arrays 502and 506, respectively. One or more of the connection pads 504 areextended to each align with a different interconnect terminal 600 (shownin FIG. 6) of the warped interconnect 602 such that the connection pads504 couple an interconnect terminal 600 with a conductive via in thesubstrate assembly 500. Any number of the connection pads 504 and/or 508can be widened, or extended, on one or both sides to accommodate theinterconnect terminals of an interconnect that may be warped.

Although connection pad layouts has been described in language specificto structural features and/or methods, it is to be understood that thesubject of the appended claims is not necessarily limited to thespecific features or methods described. Rather, the specific featuresand methods are disclosed as exemplary implementations of connection padlayouts.

1. A method, comprising: forming a substrate assembly having conductivevias; determining a warp variance of manufactured interconnects; anddisposing connection pads over the substrate assembly in a configurationaccording to the warp variance such that each of the connection pads areconfigured to align with a different terminal of a warped interconnect.2. A method as recited in claim 1, wherein disposing the connection padsover the substrate assembly includes extending one or more of theconnection pads such that each of the connection pads are configured toalign with a different terminal of the warped interconnect.
 3. A methodas recited in claim 1, wherein disposing the connection pads includesforming the connection pads as solder pads each configured to form asoldered connection that electrically couples a terminal of the warpedinterconnect with a conductive via in the substrate assembly.
 4. Amethod as recited in claim 1, wherein forming the substrate assemblyincludes forming the substrate assembly as a multilayered ceramicsubstrate assembly.
 5. A method as recited in claim 1, wherein: formingthe substrate assembly includes forming the substrate assembly with atleast a first surface; and disposing the connection pads includesdisposing the connection pads on the first surface of the substrateassembly such that each connection pad is configured to align with adifferent terminal of the warped interconnect which is warped in adirection parallel with the first surface of the substrate assembly. 6.A method as recited in claim 1, wherein: forming the substrate assemblyincludes forming the substrate assembly with at least a first surface;and disposing the connection pads includes disposing the connection padson the first surface of the substrate assembly such that each connectionpad is configured to align with a different terminal of the warpedinterconnect which has a first end that is warped in a directionparallel with the first surface of the substrate assembly.
 7. A methodas recited in claim 1, wherein: forming the substrate assembly includesforming the substrate assembly with at least a first surface; anddisposing the connection pads includes disposing the connection pads onthe first surface of the substrate assembly such that each connectionpad is configured to align with a different terminal of the warpedinterconnect which has a first end and a second end that are both warpedin a direction parallel with the first surface of the substrateassembly.